System and method for providing time to a satellite positioning system (SPS) receiver from a networked time server
First Claim
1. A method for providing time information comprising:
- sending a query to a time server via a first communications network;
determining a time-of-day from a response from the time server;
adjusting a clock if the time-of-day differs from a time maintained by the clock; and
providing the time information to a satellite positioning system (SPS) receiver via a first communications link, wherein the communications link is different from a second communications link that is used by satellites in to communicate with the SPS receiver.
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Accused Products
Abstract
System and method for enabling signal acquisition in a satellite positioning system (SPS) when signals from SPS satellites are attenuated by the operating environment of a SPS receiver. A preferred embodiment comprises a communications server (for example, communications server 220) coupled to a SPS receiver (for example, SPS receiver 210) at one end and a time server (for example, time server 225) by a public network (for example, the Internet 230). Preferably, the communications server 220 is coupled to the Internet 230 via a wireless network to facilitate maximum mobility and flexibility. The communications server 220 queries the time server 225 for the current time and then provides the current time to the SPS receiver 210. The SPS receiver 210 makes use of the current time to assist it in signal acquisition.
77 Citations
47 Claims
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1. A method for providing time information comprising:
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sending a query to a time server via a first communications network;
determining a time-of-day from a response from the time server;
adjusting a clock if the time-of-day differs from a time maintained by the clock; and
providing the time information to a satellite positioning system (SPS) receiver via a first communications link, wherein the communications link is different from a second communications link that is used by satellites in to communicate with the SPS receiver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
sending the query via the first communications network to a second communications network; and
sending the query via the second communications network to the time server.
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3. The method of claim 2, wherein the first communications network is a wireless communications network.
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4. The method of claim 3, wherein the wireless communications network is a cellular communications network.
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5. The method of claim 3, wherein the wireless communications network is a packet switched network.
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6. The method of claim 2, wherein the second communications network is the Internet.
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7. The method of claim 1, wherein the determining comprises:
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computing a latency involved with the query and the response; and
adjusting the time-of-day to compensate for the latency.
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8. The method of claim 1, wherein the time information comprises a timing pulse and a time message to the SPS receiver, wherein the timing message carries a time corresponding to the occurrence of the timing pulse.
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9. The method of claim 1, wherein the sending comprises sending a plurality of queries to a plurality of time servers, and wherein the determining comprises averaging the time-of-day received from each of the time servers.
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10. The method of claim 1, wherein the SPS is a Global Positioning System (GPS).
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11. A method for facilitating signal acquisition in a satellite positioning system (SPS) comprising:
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sending a periodic query with a first period to a time server via a communications network;
determining a time-of-day from a response from the time server;
adjusting a clock if the time-of-day differs from a time maintained by the clock; and
providing a time information based on the time maintained in the clock periodically to a SPS receiver with periodicity equal to a second period via a first communications link, wherein the first communications link is different from a second communications link that is used by satellites in the satellite positioning system (SPS) to communicate with the SPS receiver. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
counting a series of periodic beacon pulses provided by an additional clock;
comparing the number of counted beacon pulses with an expected number of beacon pulses; and
adjusting the clock if the number of counted beacon pulses and the expected number of beacon pulses are different.
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14. The method of claim 13, wherein the expected number of beacon pulses is calculated by dividing the second period with a period of the periodic beacon pulses.
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15. The method of claim 13, wherein the number of counted beacon pulses is reset after each step of providing.
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16. The method of claim 11, wherein the time information comprises a timing pulse and a timing message to the SPS receiver, wherein the timing message carries a time corresponding to the occurrence of the timing pulse.
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17. The method of claim 16, wherein the timing pulse begins at approximately a specified transmit time, and wherein the specified transmit time is a multiple of the second period.
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18. The method of claim 16, wherein the timing message carries a time corresponding to a specified transmit time.
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19. A system for aiding signal acquisition in a satellite positioning system (SPS) comprising:
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an SPS receiver containing circuitry to receive transmissions from a plurality of SPS satellites;
a communications processor coupled to the SPS receiver, the communications processor containing circuitry to obtain time information, generated by other than the SPS satellites, from an external source and to provide the time information to the SPS receiver, the SPS receiver utilizing the time information to facilitate acquisition of signals from the SPS satellites;
a first communications network coupled to the communications processor; and
a time server coupled to the first communications network, the time server containing circuitry to maintain accurate time and to respond to time queries. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A system for aiding signal acquisition in a satellite positioning system (SPS) comprising:
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a SPS receiver, the SPS receiver containing circuitry to receive transmissions from a plurality of SPS satellites and compute its current position and a current time from the received transmissions;
a communications processor coupled to the SPS receiver, the communications processor containing circuitry to obtain time information from an external source and to provide the time information to the SPS receiver;
a first communications network coupled to the communications processor; and
a time server coupled to the first communications network, the time server containing circuitry to maintain accurate time and to response to time queries, wherein the communications processor comprises;
a time server client coupled to the first communications network, the time server client containing circuitry to interface with the time server;
a real-time clock coupled to the time server client, the real-time clock to maintain a time as provided by the time server; and
a pulse and message generator (PMG) coupled to the real-time clock, the PMG containing circuitry to provide time information taken from the real-time clock to the SPS receiver. - View Dependent Claims (27, 28, 29)
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30. A position measuring device comprising:
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a satellite positioning system (SPS) receiver comprising an analog processing unit containing circuitry to filter and amplify an analog SPS signal received via an antenna;
a digital processing unit coupled to the analog processing unit, the digital processing unit containing circuitry to perform signal acquisition, correlation, and decoding;
a communications processor comprising;
a pulse and message generator (PMG) unit containing circuitry to produce a timing beacon and a timing message;
a real-time clock coupled to the PMG unit, the real-time clock containing circuitry to keep track of time and to generate signals to indicate timing events; and
a network client coupled to the real-time clock, the network client containing circuitry to receive timing information from a time server coupled to the communications processor via a network and to provide time adjustments to the real-time clock. - View Dependent Claims (31, 32, 33, 34, 35)
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36. A communications processor comprising:
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a pulse and message generator (PMG) containing circuitry to produce a timing beacon and a timing message for use by a satellite positioning system receiver;
a real-time clock coupled to the PMG, the real-time clock containing circuitry to track time and to generate signals to indicate timing events to the PMG; and
a network client coupled to the real-time clock, the network client containing circuitry to receive timing information from a time server coupled to the communications processor via a network and to provide time adjustments to the real-time clock. - View Dependent Claims (37, 38, 39, 40, 41, 42)
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43. A method for facilitating signal acquisition in a satellite positioning system (SPS) comprising:
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determining a time-of-day from a time message broadcast by a time server;
adjusting a clock to the time of day if the time-of-day differs from a time maintained by the clock; and
providing a time information based on the time maintained in the clock periodically to a SPS receiver via a first communications link, wherein the first communications link is different from a second communications link that is used by satellites in the SPS to transmit information to the SPS receiver, and wherein said SPS receiver utilizes the time information in acquisition of signals transmitted from satellites. - View Dependent Claims (44, 45, 46, 47)
counting a series of periodic beacon pulses provided by an additional clock;
comparing the number of counted beacon pulses with an expected number of beacon pulses; and
adjusting the clock if the number of counted beacon pulses and the expected number of beacon pulses are different.
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46. The method of claim 43, wherein the time server broadcasts the time message via radio signals.
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47. The method of claim 43, wherein the time server is a Network Time Protocol (NTP) compliant server.
Specification